Currently four separate areas of investigation are being performed in our laboratory aimed at understanding the mucosal immune response through studying the molecular regulatory elements involved in the immunoglobulin class switch as well as identifying factors which regulate this process at the cellular level. Project I: Creation of a knockout mouse in which a specific DNA binding site in an Ig switch regulatory enhancer is deleted using Cre-LoxP gene targeting techniques. Project II: Assess the role of IL-7 in T-dependent IgA class switching. Project III: Identifying the cytokine(s) functioning to induce resting human peripheral blood B cells to switch to the IgG2 isotype. Project IV: Assess the role of OX40L rescue of IL-6-induced cell cycle arrest and apoptosis of terminally differentiating, late-stage B cells.